PyPDF's Manipulated FlateDecode streams can exhaust RAM

Impact

An attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires just reading the file if a series of FlateDecode filters is used on a malicious cross-reference stream. Other content streams are affected on explicit access.

Patches

This has been fixed in pypdf==6.0.0.

Workarounds

If you cannot upgrade yet, you might want to implement the workaround for pypdf.filters.decompress yourself: https://github.com/py-pdf/pypdf/blob/0dd57738bbdcdb63f0fb43d8a6b3d222b6946595/pypdf/filters.py#L72-L143

References

This issue has been reported in #3429 and fixed in #3430.